DE102008008282B4 - Orthopedic foot and method for controlling an artificial foot - Google Patents

Abstract

An orthopedic foot part having a lower leg connecting part, a swivel joint (5) acting as an ankle joint (7), with which a foot part (10) is rotatably connected to the lower leg connecting part in the direction of dorsiflexion and plantarflexion, with a rotational movement about the swivel joint (5 ) with a sensor arrangement for detecting action states of the orthopedic foot part and with a sensor arrangement connected to the control, which controls the damping arrangement (17), characterized in that the sensor arrangement a the angle between lower leg connector and foot ( 10), an absolute angle sensor (20) related to the plumbing, and a moment sensor (21) for detecting the torque at the ankle joint (7) or a force inducing a torque at the ankle joint (7), and wherein the control is only by using these sensors the foot part (10) both d of a gait cycle as well as during standing only by acting on the damping arrangement (17) controls.

Description

The invention relates to an orthopedic foot part with a lower leg connecting part, acting as an ankle joint pivot, with a foot part of the foot in the direction of dorsiflexion and plantarflexion is rotatably connected to the connector, with a rotational movement about the pivot-influencing damping arrangement, with a sensor arrangement for Detection of action conditions of the artificial foot and with a controller connected to the controller, which controls the damping arrangement. The invention further relates to a method for controlling such an orthopedic foot part.

It is known that the control of an orthopedic foot part, in the form of an artificial foot or a Fußorthese, should meet numerous requirements to allow safe use of the foot and the most natural movement when walking the prosthesis wearer. Thus, it is desirable, for example, to allow controlled control of the foot part on the standing level and a controlled rolling over the forefoot while walking in heel strike, wherein the body of the prosthesis wearer is raised slightly. In the swing phase of the natural foot performs a Dorsalflexion, whereby a length shortening of the leg - and thus a facilitated swinging - is achieved. Furthermore, for a secure standing with an artificial foot is required that a high stability of the angle between the foot part and the lower leg connector is. However, a purposeful blocking of acting as ankle joint pivot joint of the artificial foot should be adjustable so that standing on a sloping ground or on a shoe with a larger heel height for the prosthesis wearer in a relaxed manner is possible.

It is for example through US 2005/0197717 A1 It is known to control the ankle angle during a gait cycle by an actuator in the form of a twin screw motor. A foot part is used, which should contribute to the realization of an approximately natural gait pattern by a defined elasticity. The use of an actuator in the form of a constantly driven motor requires significant amounts of electrical energy that must be supplied to the artificial joint. For this purpose, the prosthesis wearer must carry a powerful battery, which must be bulky and heavy due to the required high capacity.

It is also known, for the fulfillment of partial aspects of the control to control only a damping of the rotational movement of the foot part relative to the connecting part. By US 7,029,500 B2 respectively. EP 1 494 626 B1 ( DE 603 09 685 T2 For this purpose, a special swivel joint is provided as the ankle joint of the artificial foot, wherein the attenuation is influenced by a magneto-rheological fluid by the application of a magnetic field, the liquid from a low viscosity to a high viscosity - and thus the damping of a low attenuation a strong damping - is switchable. This makes it possible to lock a dorsal or plantarflexion that automatically sets during walking and to maintain it for a certain period of time. It is also achieved that the joint is released when sitting to adjust the setting of plantarflexion, as it performs the natural foot while sitting. In order to determine the gait cycle and to automatically control the joint unit, various sensors are proposed, for example a heel sensor system and a toe sensor system in order to detect the load on the foot on the heel or in the toe area and to allow conclusions about the gait cycle. Furthermore, an angle sensor may be provided to determine the angular position and possibly the angular velocity of the pivot joint acting as the ankle joint. A complete detection of the possible states when walking and standing, possibly also on a flat and a non-flat surface, is not possible by such a sensor arrangement.

By US 2002/0138153 A1 It is also known, for adjusting the angle of repose when standing on a sloping ground or for different heel heights of a shoe, which is used with the artificial foot, to use a hydraulic arrangement in which the liquid at a Plantarflexion of a liquid reservoir in the other and for a dorsiflexion flows in the opposite direction. In a connecting line between the two liquid reservoirs, an electromagnetic coil is used, which controls the viscosity of the magnetorheological fluid used as a hydraulic fluid, whereby a switching of the attenuation from a first attenuation level to a second attenuation level is possible. In order to fulfill the ordered control tasks, a tilt sensor for the lower leg part relative to the vertical and a ground contact sensor is used. The ground contact sensor indicates that the artificial foot is experiencing a floor reaction force by landing on the ground.

The present invention has for its object, an orthopedic foot part of the type mentioned so controllable to design that more demands on the properties of an orthopedic foot as before with a Only passive control of the damping of the movement around the ankle joint can be fulfilled.

This object is achieved according to the invention in an orthopedic foot part of the type mentioned, the sensor arrangement an angle between the lower leg connector and foot part measuring ankle angle sensor, related to the perpendicular absolute angle sensor and a torque sensor for detecting the torque at the ankle joint or a torque at the ankle joint has triggering force and that the control controls only by using these sensors, the foot part both during a gait cycle as well as during standing only by acting on the damping arrangement.

It turns out that the use of the only three types of sensors allows control of the artificial foot both during a gait cycle and while standing in a desired manner only by acting on the damping of the movement of the ankle joint. As will be explained in more detail below, the few sensor signals are sufficient to unambiguously determine the required different states of action of the foot and to adjust the foot to mimic the movement of a natural, healthy foot during the gait cycle while still standing upright sloping surfaces or with different heights, can give a secure feeling. It also shows that the signals of the sensors provided according to the invention are furthermore sufficient for everyday gait situations, such as the ascending and descending stairs and ramps and the backing-off can also be reliably controlled.

In a preferred embodiment, the damping arrangement has separate and separately controllable damping means in the direction of plantar flexion on the one hand and dorsiflexion on the other hand. Accordingly, the movements are separately controllable in both directions. This allows a different treatment of the attenuation in the different directions of rotation and, for example, in dependence on the output signal of the ankle angle sensor.

In the orthopedic foot part according to the invention, the foot part is completely or at least predominantly rigid. The resilient movement of the foot part in the stance phase is realized by the control of the damping of the rotational movement of the foot part relative to the lower leg connecting part. For this purpose, it is necessary that the damping arrangement is adjustable in several intermediate states, preferably is continuously adjustable. The adjustment of the damping is controlled by a corresponding program in the control, so that the movement of the foot part relative to the lower leg connection part is completely controlled. The use of elastic parts, which avoid shock-like transitions, for example when heel occurs by an elastic heel part, is not excluded.

A variation results from the fact that in a particularly preferred embodiment of the invention the foot part consists of a rigid base part connected via the ankle joint to the attachment part and a forefoot part articulated to the base part. The hinged at the front end of the base part forefoot mimics the movement of the toes of a natural foot in the toe joints, wherein the controlled by the two valves damping cylinder is hinged on the one hand on the lower leg connector and on the other hand on the forefoot near the hinge between the base part and forefoot part. Depending on the angular position of the forefoot part, this results in a more or less greatly reduced transmission of the damping effect of the damping cylinder to the rotational movement of the base part relative to the lower leg connecting part. In other words, the lever length of the base part effective for the ankle joint changes due to the kinking of the forefoot part, for example, when rolling over in the stance phase of the gait cycle. This defined shortening of the lever length of the base part is taken into account by the program in the control.

The separate control of the damping means in the direction of plantarflexion on the one hand and dorsiflexion on the other hand allows the determination of a zero point position, from which the movement in the two directions is controlled. This zero position can be manually set by a switch on the ankle joint. The switch can be a remote control switch, so the operation does not have to be on the foot.

Such a setting of the zero point is useful, for example, if the wearer of the orthopedic foot part uses this with other shoes having a changed heel height. In this way, an adjustment to the new heel height can be made without problems by manually setting the zero point. Alternatively, it is also possible that the controller detects the zero point position from the data of the sensors and that the damping means can be controlled starting from the zero point position.

In an embodiment which is preferred in practice, the damping arrangement is a hydraulic arrangement through which a hydraulic fluid flows, in which a dorsal valve is preferably used to influence the flow in the direction of dorsiflexion, and a plantar valve in the direction of plantar flexion is provided. The orthopedic foot part, in this preferred embodiment, thus has two one-way valves, through which the hydraulic fluid can flow only in one direction, so as to enable the separate controllability of the movements in both directions.

A method according to the invention for controlling an orthopedic foot part comprising a lower leg connecting part, an articulated swivel joint pivotally connecting a foot part of the foot in the direction of dorsiflexion and plantarflexion to the connecting part, a damping arrangement influencing the rotational movement about the rotary joint, a sensor arrangement for detection of action conditions of the artificial foot and having a controller connected to the control arrangement, which controls the damping arrangement, according to the invention is characterized in that the torque occurring at the ankle joint (ankle moment) proportional value, the ankle angle between the connecting part and foot part and the absolute angle of the foot part the perpendiculars are determined and that in response to these measured values, the rolling of the foot in the stance phase of walking, the position of the foot in the swing phase of walking and the position un d mobility of the foot is controlled during standing by means of the damping arrangement. If there is no dorsiflexion to a plantar flexion within a given time interval, it will stop.

The damping in the direction of dorsiflexion and the damping in the direction of plantar flexion with separate damping means are preferably controlled separately. The damping means can preferably be adjusted during the walking process in numerous intermediate positions, preferably continuously. The adjustment is carried out by a program of control for complete movement control, which is preferably not effected by material elasticities. It is essential that the adjustment of the damping means can be made taking into account the measured ankle angle or absolute angle.

The control of the movement of the foot according to the invention allows the influencing of parameters of a gait cycle by sensor signals already measured for this gait cycle. The adaptation can therefore take place directly, so that the parameters of a gait cycle need not be controlled by measured parameters of a previous gait cycle, as is known with previous active controls. For example, according to the invention it is readily possible, taking into account the absolute angle of the foot part (or taking into account the signal of the rotation angle sensor and the lower leg connection part) and the measurement signal of the torque sensor to perform a step length determination when placing the heel on the ground and in dependence on the certain step length to determine the damping parameters for the just initiated gait cycle. Depending on the particular stride length, for example, the angle of rotation of the ankle joint that is permissible from a specific zero point in the direction of dorsiflexion and plantarflexion can be varied. The limitation of the rotational movement of the ankle joint is effected by a corresponding control of the respective damping means as a function of the measured ankle joint angle.

The combination of measuring signals according to the invention also makes it possible to distinguish between walking and standing by means of a suitable evaluation of these measuring signals by a processor in the controller. Namely, the transition from walking to standing is detected when the ankle moment reaches a value near zero from a negative value and the absolute angle is zero and is maintained. In relaxed standing the lower leg or the center of gravity of the body is in the vertical. The transition from standing to walking is determined by the ankle moment being close to zero, the absolute angle exceeding a standstill threshold, and the change in absolute value exceeding a threshold over time. In this case, the measurement of the absolute angle, which reproduces the pre-swinging of the leg at the beginning of walking, can already be used for the indirect determination of the stride length, since the absolute angle occurring during pre-swinging of the lower leg is proportional to the stride length.

The method according to the invention also makes possible a suitable control of the artificial foot during the gait cycle, which will be explained in more detail below.

The described construction of the artificial foot with a foot part, which consists of a base part and an articulated to the base part associated Vorderfußteil, allows the otherwise impossible distinction between a heel height of a shoe and a correspondingly inclined ground.

While the forefoot part remains in a stretched position biased by a return spring on an inclined ground, a shoe with a high heel results in an angled position of the forefoot part relative to the base part. An additional angle sensor, which represents the angular position of the forefoot part relative to the base part, could therefore cause the distinction between "inclined ground" and "heel height".

If such a sensor is not provided, the fact that the adjustment to the heel height must be made only when putting on the shoe, by taking into account that at this time a signal is transmitted to the controller, with the zero position of the swivel joint for the current standing condition caused by the heel height is detected. Accordingly, a switching signal is provided for the control, which is preferably transferable with a remote control device from the prosthesis wearer to the controller.

Preferably, a hydraulic arrangement is used as a damping arrangement, which is traversed by a hydraulic fluid, wherein the damping means, which are provided and controlled separately for the two directions of movement, by hydraulic one-way valves (Plantarventil and Dorsalventil) are formed.

Incidentally, the sensor arrangement used according to the invention allows the determination of the respective zero point, so that an adaptation to the new zero point can already be made during the gait cycle itself.

The invention will be explained in more detail below with reference to an embodiment shown in the drawing. Show it:

1 a schematic representation of a first embodiment of a foot prosthesis according to the invention;

2 a schematic representation of a second embodiment of a foot prosthesis according to the invention;

3 a schematic representation of a third embodiment of a foot prosthesis according to the invention;

4 a plan view of a structurally detailed further embodiment of a foot prosthesis according to the invention;

5 a vertical section parallel to the sagittal plane through the prosthetic foot according to 4 ,

At the in 1 illustrated embodiment is a mounting piece 1 with an adjustment approach 2 formed in the form of a reverse truncated pyramid with four inclined surfaces. The attachment piece 1 forms a downwardly open pot into which an upwardly projecting web 3 a two-armed lever 4 protrudes. The two-armed lever is a swivel joint 5 rotatable, whose axis of rotation 6 at the same time forms the axis of an ankle joint of the artificial foot. The swivel joint 5 is with an angle sensor 7 Mistake. The two-armed lever 4 has a rigid, downwardly projecting approach 8th on.

In the downwardly open pot of the attachment piece 1 is the one with the jetty 3 formed gap by a relatively stiff, elastic material 9 filled so that the movement of the attachment piece 1 only slightly damped on movement of the bridge 3 of the two-armed lever 4 is transmitted. Accordingly, the approach is completed 8th the movement of the attachment piece 1 after, but because of the elastic material 9 something damped.

The swivel joint forming the ankle joint 5 also carries a main foot part 10 , which also acts as a two-armed lever with a rear lever arm 11 extending into the heel area of the foot where the rearward and downward rearward lever arm extends obliquely 11 with an approximately horizontally rounded end 12 is provided.

The main foot part has one from the ankle joint 5 forwardly extended front lever arm 13 on, which is almost straight from the ankle joint 5 extends from slightly sloping downwards so that the main foot part 10 to the ankle joint 5 is arched towards the top and the ankle joint 5 slants down into the heel area as well as forward into a forefoot area, wherein the sloping drop in the heel area is steeper than in the forefoot area.

The front lever arm 13 of the main foot part 10 ends at the beginning of the forefoot area and wears a swivel joint there 14 , with a forefoot part replicating a toe area 15 rotatable on the front lever arm 13 the main foot part is articulated. The swivel joint 14 has an axis of rotation parallel to the axis of rotation 6 of the ankle joint 5 runs in a horizontal direction. Because the forefoot part 15 mimicking the toe area of a natural foot, it is triangular shaped with a tip towards the front. Below the swivel joint 14 located at the forefoot part 15 another hinge 16 with which a piston rod of a piston 18 a hydraulic cylinder 17 on the forefoot part 15 is articulated. The hydraulic cylinder 17 is with a swivel 19 rotatable at the free end of the downwardly projecting lug 8th of the two-armed lever 4 hinged, so the swivel 19 below and slightly forward (towards forefoot area 15 ) offset to the ankle joint 5 is arranged.

The ankle joint 5 contains the angle sensor 7 for the measurement of the ankle angle, ie the angle between the (aligned with the Lower leg aligned) bridge 3 and the front lever arm 13 of the main foot part 10 ,

The front lever arm 13 of the main foot part 10 also carries a tilt sensor 20 , which determines the inclination relative to the gravitational force (relative to the perpendicular).

Such tilt sensors 20 , which determine an absolute inclination angle relative to the gravitational acceleration, are known as acceleration sensor arrangements with or without gyroscope.

The two-armed lever 4 contains alignment with the alignment approach 2 ie, aligned with the artificial lower leg of the patient, an ankle torque sensor 21 which measures the torque acting at this point.

The forefoot part 15 is at its rear end with a bearing neck 22 provided for holding a loadable on train and pressure spring 23 Serves, with its other end on the front lever arm 13 of the main foot part 10 supported. The feather 23 causes a provision of the forefoot part 15 after a Dorsalflexion, wherein the return speed through the hydraulic cylinder 17 is determined.

The hydraulic cylinder 17 can be designed as a passive actuator in which the piston 18 caused hydraulic flow is controlled by (not shown) valves, the valves themselves are not only switched on and off, but can also be controlled for a defined flow rate. But it is also possible, the hydraulic cylinder 17 form as an active actuator, the force from the outside without an adjustment of the forefoot part 15 can cause.

In the 2 illustrated embodiment substantially corresponds to the embodiment according to 1 , One difference is that the attachment piece 1' with the adjustment approach 2 is integrally formed, so that a through the elastic material 9 formed elasticity is no longer present. Instead, the downward-facing approach 8th' of the two-armed lever 4 ' formed with a dilution of material, so that the swivel 19 supporting free end of the approach elastically resilient to the remaining material of the two-armed lever 4 ' is arranged.

Of course, the artificial foot according to the second embodiment also has a cosmetic coating 24 on, as the first embodiment. This cosmetic cover 24 however, is not shown repeatedly for the second and third embodiments.

In the artificial foot according to the in 3 illustrated third embodiment is the two-armed lever 4 '' also in one piece with the adjustment approach 2 educated. Also the downwardly projecting approach 8th of the two-armed lever 4 '' is rigid as in the first embodiment. Instead, the hydraulic cylinder 17 via a spiral spring 25 elastic with the downwardly projecting neck 8th of the two-armed lever 4 '' connected. This will be in series with the action of the hydraulic cylinder 17 an elasticity realized in the in 1 illustrated embodiment by the elastic material 9 and at the in 2 illustrated embodiment by the resilient approach 8th' is realized. All other parts of the third embodiment are the same as those of the first embodiment.

That in the 4 and 5 illustrated embodiment leaves the attachment piece 1 with the pyramidal adjustment approach 2 detect. In the attachment piece 1 is the elastic material 9 with the upstanding bridge 3 of the two-armed lever 4 cooperates damping. The downward-facing approach 8th of the two-armed lever 4 runs in this embodiment in Gehrichtung behind the ankle joint 5 and is there over the hinge 19 on the hydraulic cylinder 17 hinged. In the hydraulic cylinder 17 The piston moves longitudinally displaceable 18 , one in the hydraulic cylinder 17 located warehouse 26 led out and with the other hinge 16 of the forefoot part 15 connected is. The ankle joint 5 also stores the main foot part 10 , which is formed here in the form of a rigid housing and a rearwardly directed elastic lever 11 as a heel lever. The foot part 10 is with the heel lever 11 thus together around the ankle joint 5 relative to the attachment piece 1 and to the two-armed lever 4 pivotable. The pivoting movement between the attachment piece 1 and the foot part 10 gets over the two-armed lever 4 and the hydraulic cylinder 17 controlled and damped. The articulation of the piston rod 18 ' of the piston 18 on the forefoot part 15 only causes additional control of the forefoot part forming the toe plate 15 However, the control of the main foot part 10 only slightly modified, as the other hinge 16 in the immediate vicinity of the swivel joint 14 between the forefoot part 15 and the main foot part 10 is arranged. The hydraulic cylinder 17 is with two control valves 27 . 28 provided on the top of the hydraulic cylinder 17 are arranged. The control valves 27 . 28 are with chambers 29 . 30 of the hydraulic cylinder 17 on both sides of the piston 18 connected, with (not shown) check valves ensure that by the first control valve 27 only a flow of hydraulic fluid from the lower chamber 29 to the front chamber 30 can be done, reducing the insertion movement of the piston 18 in the hydraulic cylinder 17 allows for plantarflexion of the main foot part 10 opposite the attachment piece 1 equivalent. The other control cylinder 28 allows with check valves only the hydraulic flow from the front chamber 30 in the rear chamber 29 , thereby pulling out the piston 18 from the hydraulic cylinder 17 allows, so an extension of the distance between the hinges 19 . 16 takes place. This corresponds to a Dorsalflexion between the attachment piece 1 and the main foot part 10 , At the same time, by the displacement of the swivel joint 16 opposite the hinge 14 forward lifting of the forefoot part 15 causes. The function of the artificial foot is the same for the illustrated embodiments. With the sensor arrangement for measuring the ankle angle, the ankle moment and the absolute inclination angle, the relevant functional states of the artificial foot can be determined and differentiated, wherein the signal of the ankle angle sensor for determining the ankle angle (between attachment piece 1 . 1' . 1'' and main foot part 10 On the one hand and the respective ankle angle velocity on the other hand are evaluated.

For example, the detection of whether or not the artificial foot is being walked on can be made by determining the ankle angular velocity at the zero crossing of the ankle moment. If the ankle angular velocity in the zero crossing of the ankle moment is below a threshold value, this is recognized as "standing" and the actuator in the form of the hydraulic cylinder 17 set by the valves to a high resistance, through which a dorsal stop can be formed.

The detection of a sloping slope or heel height is made by the inclination sensor 20 in the midfoot area of the main foot part 10 determined at the zero crossing of the ankle moment.

When in-plane walking is detected, the valve responsible for plantarflexion of the foot is left in a semi-open position, while the valve that determines dorsiflexion is closed with increasing ankle angle to form a dorsal stop.

If walking is detected uphill, there is an extended dorsiflexion of the forefoot part 15 authorized.

If the heel strike after the swing phase and at the beginning of the stance phase is detected by a negative ankle moment in particular, the plantarflexion valve is controlled so that it closes with increasing ankle angle in the direction of plantarflexion and forms a stop for plantarflexion.

If a toe impact is detected at the end of the stance phase (falling ankle moment with an increased ankle angle), the valve for dorsiflexion after a dead time is fully opened to trigger the lifting of the forefoot part (toe lift) in the swing phase by an elastic element.

It can be seen from these examples that the important controls of an artificial foot during standing and walking can also be appropriately made as a function of the floor inclination or the heel height, the control of the movement resistance via the hydraulic cylinder already being sufficient. Alternatively, however, an active actuator in the sense of an actuator can be provided.

In one exemplary embodiment for the detection of the states of motion for the prosthetic foot and the resulting control, the following functions are realized:

Distinction standing-walking

• 1. Erkennung einer Schwungphase Eine Schwungphase wird dadurch erkannt, dass das Knöchelmoment nahe Null ist, da der Fuß in der Schwungphase unbelastet ist. Der Absolutwinkel des Fußteils 10 überschreitet einen Schwellenwert, der für das Stehen individuell definiert sein kann. Ferner überschreitet die Absolutwinkelgeschwindigkeit einen definierten Schwellenwert.
• 2. Erkennen eines Fersenauftritts im vorgeschwungenen Zustand Es wird ein negatives Knöchelmoment (plantarflektierend) detektiert. Das Absolutwinkelsignal entspricht einem vorgeschwungenen Fuß im Vergleich zu einem für das Stehen individuell definierten Schwellenwert. Optional kann eine Plantarflexion beim Fersenauftritt über die Knöchelwinkelgeschwindigkeit angezeigt werden.
• 3. Rückkehr zum Stehen Nach einem detektierten Fersenauftritt verbleibt der Absolutwinkel des Fußteils 10 innerhalb eines für das Stehen individuell definierten Schwellenwertes. Alternativ oder ergänzend kann eine aktive Umkehr der Bewegungsrichtung in der mittleren Standphase von dorsal nach plantar als Kriterium für das Stehen erkannt werden. Beim detektierten Stehen werden die Steuerventile 27, 28 so eingestellt, dass sich für das Stehen Anschläge nach ventral und dorsal für einen engen Winkel (Nullpunktlage) ergeben. Für den Gangzyklus wird der Anschlag nach dorsal verschoben und die Dämpfungseigenschaften für die Plantar- und Dorsalflexion in Abhängigkeit von der Schrittlänge eingestellt.

The distinction between standing and walking is based on the following criteria:

• 1. Detection of a swing phase A swing phase is detected by the fact that the ankle moment is close to zero, since the foot is unloaded in the swing phase. The absolute angle of the foot part 10 exceeds a threshold that can be individually defined for standing. Furthermore, the absolute angular velocity exceeds a defined threshold.
• 2. Recognition of a heel strike in the pre-warmed state A negative ankle moment (plantarflexing) is detected. The absolute angle signal corresponds to a prescreened foot compared to a threshold individually defined for standing. Optionally, a plantar flexion at the heel strike can be displayed via the ankle angle velocity.
• 3. Return to standing After a detected heel appearance, the absolute angle of the foot remains 10 within a threshold individually defined for standing. Alternatively or additionally, an active reversal of the direction of movement in the middle stance phase from dorsal to plantar can be recognized as a criterion for standing. When detected standing, the control valves 27 . 28 adjusted to give stops for ventral and dorsal for a narrow angle (zero point) for standing. For the gait cycle, the stop is moved posteriorly and the damping properties for the plantar and dorsiflexion are adjusted as a function of the stride length.

Distinction level-ramp

The measured absolute angle at the beginning of the middle stance phase in the walking cycle, ie after placing the full foot on the ground, is greater or smaller than a value range defined for walking in the plane for the absolute angle.

According to the determined inclination of the ramp, the dorsal stop is changed and the damping characteristics in the plantar flexion and the dorsiflexion are adjusted depending on the absolute angle and the predicted stride length.

Detection Backward

• 1. Erkennung einer Rückschwungphase Bei einem gemessenen Knöchelmoment nahe Null entspricht das Absolutwinkelsignal einem gegenüber dem Stehen zurückgeführten Fuß (Retroversion) und die Absolutwinkelgeschwindigkeit überschreitet einen definierten Schwellenwert.
• 2. Erkennung des Vorderfußauftritts im rückgeführten Zustand Gemessen wird ein größeres positives Knöchelmoment. In Abhängigkeit von den gemessenen Werten wird der Anschlag nach dorsal verstellt und die Dämpfungseigenschaften bei Plantar- und Dorsalflexion werden in Abhängigkeit vom Absolutwinkel bei dem Vorfußauftritt eingestellt.

Recognition of backward walking consists of detecting the backswing phase and detecting a forefoot occurrence in the returned state.

• 1. Detection of a backswing phase For a measured ankle moment near zero, the absolute angle signal corresponds to a foot returned to standing (retroversion) and the absolute angular velocity exceeds a defined threshold.
• 2. Recognition of the forefoot occurrence in the recirculated state Measured is a larger positive ankle moment. Depending on the measured values, the stop is adjusted posteriorly and the damping properties in the case of plantar and dorsiflexion are adjusted as a function of the absolute angle at the forefoot occurrence.

Adaptation to different heights

Preferably, the heel height is determined by reading the absolute angle signal during a manually triggered trigger signal. Proportional to the absolute angle becomes the zero point for the control valves 27 . 28 set.

Alternatively, it is possible, the heel height of a ramp slope in an artificial foot with a hinged forefoot part 15 by determining that the angle of the forefoot part 15 in relation to the main foot part 10 is measured. This is an additional option within the scope of the present invention.

Standing on inclined ground

The absolute angle is measured in a reversal of the direction of movement from plantar to dorsal, when the ankle moment undergoes a zero crossing. Accordingly, the dorsal stop for the control of the hydraulic cylinder 17 with the control valves 27 . 28 adjusted depending on the background inclination.

Detecting stairs

If the absolute angle sensor 20 consists of two acceleration sensors for mutually perpendicular acceleration components and the acceleration components can be output separately, the vertical distance traveled and the horizontally traveled path of Hauptfußteils 10 be determined. The distances are determined by two-fold integration via the corresponding acceleration components. In these cases, it is possible to make a distinction between stairway and stairway departure and adjust accordingly the stops for the damping properties in plantar and Dorsalflexion.

Similarly, the accelerations can be exploited to adjust walking at different speeds by adjusting the dorsal stops as well as the plantar and dorsiflexion damping characteristics accordingly.

Claims (31)

Orthopedic foot part with a lower leg attachment, one as ankle joint ( 7 ) acting swivel joint ( 5 ), with which a foot part ( 10 ) in the direction of dorsiflexion and plantarflexion is rotatably connected to the lower leg connecting part, with a rotational movement about the rotary joint ( 5 ) influencing damping arrangement ( 17 ), with a sensor arrangement for detecting action states of the orthopedic foot part and with a sensor arrangement connected to the controller, the damping arrangement ( 17 ), characterized in that the sensor arrangement a the angle between the lower leg connector part and the foot part ( 10 ) measuring ankle angle sensor, an absolute angle sensor related to the perpendicular ( 20 ) and a moment sensor ( 21 ) for determining the torque at the ankle joint ( 7 ) or a torque at the ankle joint ( 7 ) triggering force and that the control only by using these sensors the foot part ( 10 ) both during a gait cycle and during standing only by acting on the damping arrangement ( 17 ) controls. Orthopedic foot part according to claim 1, characterized in that the absolute angle sensor ( 20 ) consists of two acceleration sensors for mutually perpendicular acceleration components and that the measured acceleration components can be output separately and used to control the foot part. Orthopedic foot part according to claim 1 or 2, characterized in that the damping arrangement ( 17 ) has separate and separately controllable damping means in the direction of plantar flexion on the one hand and Dorsalflexion on the other. Orthopedic foot part according to one of claims 1 to 2, characterized in that the foot part ( 10 ) is rigid. Orthopedic foot part according to one of claims 1 to 3, characterized in that the foot part ( 10 ) has a rigid body, from which extends an elastic heel part. Orthopedic foot part according to one of claims 1 to 5, characterized in that the damping arrangement ( 17 ) is adjustable in several intermediate states. Orthopedic foot part according to claim 6, characterized in that the damping arrangement ( 17 ) is continuously adjustable. Orthopedic foot part according to one of claims 1 to 7, characterized in that a switch for determining a zero point position of the ankle joint ( 7 ) is provided. Orthopedic foot part according to claim 8, characterized in that the switch is designed as a remote control switch. Orthopedic foot part according to one of claims 3 to 7, characterized in that a zero position by the controller from the data of the sensors can be seen and that the damping means are controlled starting from the zero point position. Orthopedic foot part according to one of claims 1 to 10, characterized in that the damping arrangement ( 17 ) is a hydraulic system through which hydraulic fluid can flow. Orthopedic foot part according to claim 11, characterized in that for influencing the flow in the direction of dorsiflexion, a Dorsalventil and in the plantarflexion plantar valve is present. Orthopedic foot part according to one of claims 1 to 12, characterized in that the foot part ( 10 ) to the swivel joint ( 5 ) connected base part and thus via a rotary joint ( 14 ) connected forefoot part ( 15 ) and that an additional angle sensor is present, the angular position of the Vorderfußteils ( 15 ) relative to the base part. Method for controlling an orthopedic foot part comprising a lower leg attachment, an ankle joint ( 7 ) acting swivel joint ( 5 ), with which a foot part ( 10 ) is rotatably connected to the connecting part in the direction of dorsiflexion and plantarflexion, one of the rotational movement about the pivot ( 5 ) influencing damping arrangement ( 17 ), a sensor arrangement for detecting action states of the orthopedic foot part and a controller connected to the sensor arrangement, the damping arrangement ( 17 ), characterized in that an at the ankle joint ( 7 ) occurring torque proportional value, the ankle angle between the connection part and foot part ( 10 ) and the absolute angle of the foot part ( 10 ) are determined in relation to the perpendiculars and that depending on only these measured values, the rolling of the foot in the stance phase of walking, the position of the foot part ( 10 ) in the swing phase of walking and the position and mobility of the foot part ( 10 ) during standing only by acting on the damping arrangement ( 17 ) is controlled. A method according to claim 14, characterized in that are used and controlled to control the damping in the direction of dorsiflexion and plantarflexion in the direction of separate damping means. A method according to claim 15, characterized in that the damping means during the walking process in numerous intermediate positions, preferably continuously adjusted. A method according to claim 16, characterized in that the adjustment of the damping means until the blocking of the rotary joint ( 5 ) taking into account the measured ankle angle and / or absolute angle. Method according to one of claims 14 to 17, characterized in that the influencing of parameters of a gait cycle is performed by already measured for this gait cycle sensor signals. A method according to claim 18, characterized in that the influence parameters of the stance phase of the gait cycle by already measured sensor signals for the same stance phase takes place. Method according to one of claims 14 to 19, characterized in that during the stance phase of the gait cycle maximum ankle angles are set for the dorsiflexion and that the damping means in question increasingly increases its attenuation value in the direction of blocking when approaching the maximum ankle angle. Method according to one of claims 14 to 20, characterized in that during the stance phase of the gait cycle the damping means for the movement in the direction of plantar flexion is progressively increased with increasing ankle angle in this direction in its attenuation value. Method according to one of claims 14 to 21, characterized in that a state "heel strike" is detected by the occurrence of a negative torque at the ankle joint in connection with an ankle angle movement in the direction of plantar flexion. Method according to one of claims 14 to 22, characterized in that for standing a high progression of the damping values of the damping means is already set for small angles near the zero point. A method according to claim 23, characterized in that the zero point is determined in dependence on the inclination of a support surface of the foot or the heel height of a shoe. A method according to claim 24, characterized in that the zero point adjustment takes place when the torque at the ankle joint, starting from a negative value, has reached a value greater than zero. Method according to one of claims 14 to 25, characterized in that the heel counteracting the damping means is controlled in the direction of plantarflexion up to a maximum damping value and that the transition to a positive torque at the ankle joint, the damping means in the direction Dorsalflexion for the controlled return of plantarflexion and Training a stop is controlled. Method according to one of claims 14 to 26, characterized in that at the beginning of the swing phase of the gait cycle by means of a return spring a provision in Dorsalflexionsrichtung is made by reducing the value of the damping means in the dorsal direction, so that when heel occurrence at the end of the swing phase Dorsalflexion of the foot ( 10 ) is present. Method according to one of claims 14 to 27, characterized in that as a foot part ( 10 ) a connected to the pivot base part and thus via a rotary joint ( 5 ) connected forefoot part ( 15 ) is used. A method according to claim 28, characterized in that in addition an angle measurement for the forefoot angle of the forefoot part ( 15 ) is made relative to the base part. A method according to claim 29, characterized in that between an inclination of the ground to the front and a raised shoe heel by determining the angle between the base part and forefoot part ( 15 ) is distinguished. Method according to one of claims 14 to 30, characterized in that two acceleration sensors for mutually perpendicular acceleration components are used for the determination of the absolute angle and that the signals of the acceleration sensors are output separately and used for the control of the orthopedic foot part.

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